Due to oncoming thunderstorms, rain, heat, and about 150% humidity, our MAPS banding operations at BSBO were cut short a little bit early today. From the little time we did band, however, we were able to gather that more young Yellow Warblers are on the move with their parents, there are already some completely molted (into formative plumage) hatching-year (HY) YEWAs roaming around on their own, and young Gray Catbirds are just starting to leave the nest, still in their complete floofy juvenal plumage. But our best surprise this morning was a bird we don't often have at BSBO during the summer....American Redstart. 

​Without catching young or locating a nest, we can't positively say that AMRE have bred at BSBO this summer. The more likely scenario is that this (and other AMRE we've heard this summer and past summers) are simply un-mated birds moving through the region, or birds that have already fledged young somewhere else and are preparing for migration.

Unlike migration banding, summer banding offers us a glimpse of birds in active molt - a fairly short period in a bird's life cycle. But due to the plumage differences in male AMRE, this bird's molt was exceptionally interesting! 

Male AMRE have delayed plumage maturation, meaning that HY and second-year (SY) birds look completely different than their adult counterparts. In AMRE, young males are gray with yellow accents, gaining minute black splotches by their first spring. Whereas adult males are black with orange accents. This plumage difference always makes aging adult male AMRE simple: if the bird is black and orange in spring, it's an after-second-year (ASY); if its black and orange in the fall, its an after-hatching-year (AHY). During the pre-basic molt in late summer, young males will begin replacing their gray and yellow feathers for black and orange feathers, producing the bird's definitive basic (or adult) plumage. The bird we captured today is undergoing that molt right now, showing off a very unique look during this transitional phase. 

While in active molt, an accurate age can often be difficult to discern, and sometimes we simply have to say that it's an AHY bird (we don't know when it was hatched, but it wasn't this year). But despite being in active molt, due to the species' delayed plumage maturation, we were able to confidently age this male AMRE as an SY (a bird hatched last year). Black feathers in the head, tertials, greater coverts, primary coverts, inner primaries with orange, and rectrices are all recently replaced, basic feathers. The remaining gray/brown back and face feathers, secondaries with yellow, alula, and outer primaries are retained juvenal feathers (formative for the body feathers). If this were an ASY male AMRE, he would be replacing basic feathers for new basic feathers...black and orange feathers, for new black and orange feathers.    

Due to the obvious difference in feather ages, our fingers are crossed that this scruffy lad will stick around the area long enough for us to reacapture him and track his advancement in molt, documenting this often unseen and short lived period. In another week or so, this bird will look completely different than today. Gaining all black feathers with orange accents. Because of the timing of this capture, we've added another point of information to the record of this bird, and subsequent recaptures will keep track of his exact age. And, while he may look a "hot mess," isn't this guy just too cool looking!?   

As we continue to gather and analyze the data from this year's spring banding season, we've been hard at work operating two MAPS stations: One located in the restored oak/dogwood shrub-scrub habitat along the Gallagher trail behind the BSBO headquarters. And the second, in a portion of the Oak Openings Preserve Metropark that encompasses sand dune, oak forest, shrub-scrub, and degraded grassland habitats. 

We are about mid-way through the summer season and have encountered some great birds at both stations including American Woodcock, all the Yellow Warblers at BSBO, Cedar Waxwing, Summer Tanager, Ovenbird, and Lark Sparrow. This is such a great and unique time to work with birds - for a multitude of reasons - but chiefly: compared to migration, the return rate of breeding birds is much higher, allowing us to compare individuals from year to year and hone our aging and sexing skills; and both young and adult birds are molting, allowing us to document the patterns of species and the irregularities of individuals. 

While we would love to write something about each species (and sometimes each bird!) we encounter during the breeding season, there simply isn't enough time or available space on the server to allow for such lengthy posts. However, a few birds each session always tend to catch our eye.         

​This HY Yellow Warbler banded June 25th at BSBO,  has recently left the nest and is still in nearly full juvenal plumage (or first-basic plumage). This first set of body feathers (not often seen in the field) is grown quickly after hatching, providing the young bird with just enough protection and camouflage while it remains in and near the nest. The quality of these feathers is quite low, giving the bird a matte and floofy appearance. After fledging, HY birds will quickly roll into their pre-formative molt, replacing their body feathers and some wing covert feathers (depending on the species). In the case of Yellow Warblers, HY birds will attain higher quality yellow body feathers in their pre-formative molt, giving them the distinct look of the species and separating their plumage as male or female. Because flight feathers are of heavier construction and require more energy to grow (compared to body feathers), many HY birds (including the majority of species of passerine) will retain their juvenal primaries, primary coverts, secondaries, and rectrices through the pre-formative molt, eventually replacing them during the pre-basic molt the following year.

​Caught together at Oak Openings, this (presumed) family group of Tufted Titmouse represent three generations of birds. From left to right we have a third-year male TUTI, an HY TUTI (the presumed offspring), and a second-year female TUTI. Despite being quite similar in appearance, the HY bird is still in full juvenal plumage, showing loose, floofy body feathers, a yellow gape, and a pinkish bill base. Male and female TUTI are identical by plumage, and males will develop a brood patch, making it difficult to sex individual birds. Luckily, these birds were captured together and we were able to differentiate physical breeding signs between the two adult birds, separating them as male and female. Due to the nature of molt, we are only able to accurately age most species of birds we encounter into their second year (as most birds will replace all of their feathers at the end of their second summer, showing a single generation of feathers). The adult male TUTI however, was a recapture, previously banded as a hatching-year bird in 2016, putting him in his third-year of life. Without having been previously banded we would only be able to call him an after-second-year bird (a bird hatched prior to last year), based on his feathers. His feathers can only tell us that he's at least older than a second-year, but his band and the associated data can give us a picture of his movements and life at the Oak Openings station.  

​Over the past 50 years, the Golden-winged Warbler has seen one of the sharpest population declines of any songbird species, and is in consideration for Endangered Species classification. The expansion of the Blue-winged Warbler and hybridization with Golden-wingeds has been identified as a contributing factor to the decline in GWWA numbers. However, the primary threat (as well as to a number of other species) is habitat loss both on the breeding grounds in North America and wintering grounds in Central and South America.

Due to high precipitation and strong north-easterly winds this past winter, the marsh is pretty...well….marshy. Much of the station has higher than average water levels and muck boots are a requirement to reach some of the nets. But due to this high water level, we have doubled another species’ capture record (going from one ever caught, to two captured in a week): Belted Kingfisher. Kingfishers generally don’t enter the marsh too often, but with high water levels near the nets, we were perfectly poised to catch them as they darted through openings in the buttonbush. ​

Text and photo by BSBO Passerine Research Technician, Arthur Sanchez Jr.

The above cases represent only a few of the trend patterns we observe in the birds we study and some of the factors that may affect these species each fall. The importance of tracking these birds consistently, annually, and over the long term cannot be overstated for helping us understand how overall bird populations are faring and what factors affect bird populations. Banding birds gives us reliable and extensive empirical data to this end, data that surveys or field observations cannot provide. By combining our banding effort with consistent survey results, our data become even stronger and more robust, and paint a better, truer picture of fluctuations and trends in the bird populations we so dearly care for. It becomes an essential piece of the conservation puzzle, as only when armed with this basic information can we begin to open the door to conversations about bird conservation.​

As we reflect back on another successful fall banding season we give thanks to the birds that provide us a window into the health of our ecosystems and serve to lift our spirits. Scientifically and spiritually, birds take us to new heights and no matter how many Red-winged Blackbirds we see or how many Swainson’s Thrushes we have the privilege of examining up close, we never lose sight of how important these individual birds are to birders, researchers, and the ecosystems we work to protect.

​Following a week of warm southern winds, we were excited for a weather shift last week, that would bring cold winds down from the north. While we were expecting to see a final bump of late-September migrants that we hadn’t seen yet (specifically large numbers of Blackpoll Warbler), we were quite surprised to get a wave of October migrants including our 25th warbler species for fall, Myrtle Warbler. Since that wind shift, we have seen a quick rise in Slate-colored Junco, White-throated Sparrow, Yellow-bellied Sapsucker, Winter Wren, both kinglet species, Brown Creeper, Rusty Blackbird, and Hermit Thrush.

But by far, the coolest bird we were able to work with recently was a first-ever capture for the station...Wilson’s Snipe. While we do occasionally catch American Woodcock, we don’t regularly see shorebirds in the station, so the snipe made for an exciting and educating morning. ​